/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.storageengine.rescon.memory;

import org.apache.iotdb.db.storageengine.dataregion.memtable.IMemTable;
import org.apache.iotdb.db.storageengine.dataregion.memtable.PrimitiveMemTable;

public class MemTableManager {
  private int currentMemtableNumber = 0;

  private MemTableManager() {}

  public static MemTableManager getInstance() {
    return InstanceHolder.INSTANCE;
  }

  public synchronized IMemTable getAvailableMemTable(String storageGroup, String dataRegionId) {
    currentMemtableNumber++;
    return new PrimitiveMemTable(storageGroup, dataRegionId);
  }

  public int getCurrentMemtableNumber() {
    return currentMemtableNumber;
  }

  public synchronized void decreaseMemtableNumber() {
    currentMemtableNumber--;
    notifyAll();
  }

  public synchronized void close() {
    currentMemtableNumber = 0;
  }

  private static class InstanceHolder {

    private static final MemTableManager INSTANCE = new MemTableManager();

    private InstanceHolder() {}
  }
}
